Maxwell wrote:

It's certainly legal, but the question is, what is their intent? Do they
really resent your leaving a car or bicycle behind while you go flying, or
are they just trying to keep the their hangers from becoming clutter barns?

Storing bicycle(s), especially folding, that actually travel in the
plane may be allowed, if requested in a business-like manner.

Some hangars really do become a mess, so I can see a point.

Perhaps you could work to have the wording changed to something like:
"Items not related to aviation or airport activity"?

Folders are aviation related, and a get around or to the field bicycle
is related to airport activity. Other bikes are simply stored
household items.